linux-kernel - Re: [PATCH 0/4] x86: Add Cache QoS Monitoring (CQM) support

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Message-ID: <20140106110803.GA5623@twins.programming.kicks-ass.net>
Date:	Mon, 6 Jan 2014 12:08:03 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Tejun Heo <tj@...nel.org>,
	Li Zefan <lizefan@...wei.com>,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] x86: Add Cache QoS Monitoring (CQM) support

On Fri, Jan 03, 2014 at 12:34:41PM -0800, Peter P Waskiewicz Jr wrote:
> The CPU features themselves are relatively straight-forward, but
> the presentation of the data is less straight-forward.  Since this
> tracks cache usage and occupancy per process (by swapping Resource
> Monitor IDs, or RMIDs, when processes are rescheduled), perf would
> not be a good fit for this data, which does not report on a
> per-process level.  Therefore, a new cgroup subsystem, cacheqos, has
> been added.  This operates very similarly to the cpu and cpuacct
> cgroup subsystems, where tasks can be grouped into sub-leaves of the
> root-level cgroup.

This doesn't make any sense.. From a quick SDM read you can do pretty
much whatever with those RMIDs. If you allocate a RMID per task (thread
in userspace) you can actually measure things on a task basis.

>From then on you can use perf-cgroup to group whatever tasks you want.

So please be more explicit in why you think this doesn't fit into perf.
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